The present invention is generally concerned with a method of and an apparatus for classifying color films according to type. More particularly, the invention relates to a method and an apparatus for classifying color films which differ from one another in their response to exposure to radiation. In a more specific aspect, the invention is concerned with a method and an apparatus for use in selecting the amounts of radiation of different wavelength to which a color film is to be exposed during the production of copies therefrom.
In the course of copying color originals in automatic color printers or similar copying machines, it was heretofore customary to sort the films by manufacturer prior to copying, even if these color films could be developed by the same chemical process. This sorting is desirable, and may even be necessary, since optimum results during copying may require exposures differing considerably from those of the calibrating original used to object the color printer or similar copying machine. The coloring dyes of films stemming from different film manufacturers often exhibit, different spectral transmission characteristics after development. In order to be able to process films having different spectral characteristics using only one measuring arrangement having predetermined spectral properties, conventional printer are designed to convert the measured values into values which correspond to the spectral characteristics responses of the particular color film being used. This is usually achieved by adjusting each color channel of the photoelectric exposure control arrangement by means of adjustable or replaceable resistors known as slope storage units. In this manner, the measured values are adjusted to the particular type of film from which copies are to be made so that optimum results are achieved.
When it is desired to produce copies from color films at high speed, the color films are joined at their ends to form a strip which is wound onto a roller or reel. In order to obtain optimum copies under these circumstances, it was previously necessary for all of the films in any strip to be of the same type. This, of course, required classification of the films by type prior to copying and the production of a separate strip for each type of film even though the same chemical process was used for developing the different types of film. Such classification constitutes an additional step in the processing of the films and results in certain difficulties, particularly as regards organization of the processing operation as well as increased labor costs.